Platoon travel systems are generally known. For example, a patent document 1 (i.e., Japanese Patent No. 3358403) describes a departure process and a post-departure auto-drive process for a platoon travel control apparatus. When an in-front vehicle, such as a vehicle at the top (or “front) of a platoon, is planning to depart from the platoon, the system may slightly decelerate a self-vehicle, such as the second vehicle from the top of the platoon, and fix its speed so that the self-vehicle cruises at a constant speed. Further, when a joining vehicle is traveling in front of the self-vehicle, the platoon travel control apparatus increases an inter-vehicle distance to the joining vehicle for the ease of joining the other vehicles.
However, if the self-vehicle is the third vehicle or further behind in the platoon, the above-mentioned platoon travel control apparatus controls the self-vehicle to accelerate in order to catch up to the top vehicle and to resume the original formation of the automatic platoon travel.
In a platoon involving many vehicles, each vehicle may have different travel outputs (e.g., different horsepower output), respectively. A high travel output vehicle has a higher travel output than a low travel output vehicle in relative terms. Therefore, the above-mentioned platoon travel control apparatus may position a high travel output vehicle in front of a low travel output vehicle. Further, when traveling under the same travel resistance, the low travel output vehicle consumes more travel energy than the high travel output vehicle.
Therefore, the above-mentioned platoon travel control apparatus accelerates the low travel output vehicle to a speed that is equal to or greater than a normal platoon travel speed when the low travel output vehicle is traveling as a follow/behind vehicle in the platoon. As such, the travel energy of the low travel output vehicle is wasted. In other words, by the acceleration of the low travel output vehicle under control of the above-mentioned platoon travel control apparatus, the energy consumption of the whole platoon may be increased.
Further, the respective vehicles which have participated in the platoon have respectively different remaining energies. Therefore, the above-mentioned platoon travel control apparatus may position a low remaining energy vehicle behind a high remaining energy vehicle. The high and low remaining energies mean that the high remaining energy vehicle has a higher remaining energy than the low remaining energy vehicle in relative terms.
Therefore, the above-mentioned platoon travel control apparatus accelerates the low remaining energy vehicle to a speed that is equal to or greater than the normal platoon travel speed when the low remaining energy vehicle is traveling as a follow/behind vehicle in the platoon. As a result, even when joining in a platoon and performing a platoon travel, the low remaining energy vehicle may not be able to extend its travel distance due to the low energy consumption reduction effects.